Internal combustion engines (ICE) currently employ one of several different thermostat designs that control the flow of coolant from the engine block to the radiator. All of these designs, while different in operation, work by the same principle. When the engine coolant reaches a prescribed temperature (for example, 90° C.), the thermostat opens and allows coolant to flow from the engine block to the radiator. All of the current engine thermostats are of an on/off nature by design; either the thermostat is fully open and allows coolant to flow, or it is closed and prohibits flow. With such thermostats, there is no way to alter or vary the amount of coolant flowing from the engine to the radiator based upon engine coolant temperature.
In some applications, for example to improve engine efficiency and especially to reduce undesirable engine emissions upon engine start up, it may be advantageous to vary the flow of coolant fluid based on engine temperature to thereby vary the engine temperature within a desirable range. Such a variable flow is not possible with present thermostats. Accordingly, a need exists for a variable flow thermostat and for a method for variably controlling the temperature of an internal combustion engine.
Reference is made in the description, and with reference to the figures, to terms such as “up,” “down,” “upward,” “downward,” “upper,” “vertical,” and the like. Such terms are used only to facilitate description of the invention and are not to be taken as limiting. As those of skill in the art will appreciate, a variable flow thermostat in accordance with the invention may be operated in any spatial orientation.